CISA Issues “Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators”

In today’s increasingly interconnected industrial landscape, operational technology (OT) systems are no longer isolated islands of automation—they’re deeply entwined with information technology and business networks, making them prime targets for cyber threats. Recognizing this growing risk, the US Cybersecurity and Infrastructure Security Agency (CISA) collaborated with three US federal agencies, five international partners, and received contributions from twelve private-sector stakeholders to develop and publish “Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators.”

This resource is intended to help owners and operators of OT systems create stronger, more secure infrastructures by building a clear inventory and classification of their assets. By identifying, organizing, and managing OT assets effectively, organizations can not only improve cybersecurity but also enhance operational reliability, safety, and resilience.

Through the Joint Cyber Defense Collaborative (JCDC), CISA collaborated closely with critical infrastructure owners, operators, and other stakeholders to identify systemic gaps and critical needs across the evolving cyber threat landscape and worked hand-in-hand to co-develop effective and impactful solutions. CISA coordinated technical reviews from industry, federal, and international stakeholders across multiple sectors to ensure the guidance is relevant and applicable.

An OT asset inventory is a dynamic list containing an updated map of the devices, systems, and software that make up the operational backbone of critical environments. From industrial control systems to sensors, HMIs, servers, and specialized applications, every component plays a role in the broader ecosystem. Without visibility into these assets, organizations are effectively operating without a full view of their potential vulnerabilities.

When implemented effectively, an asset inventory becomes more than a record; it’s a strategic tool. It helps organizations uncover interdependencies across their environment, assess risk, segment networks to limit or eliminate lateral movement, and strengthen overall resilience. Achieving that level of control is possible for operators nationwide, but it demands a disciplined, consistent approach to managing one’s environment. This guide is intended to help organizations establish and maintain the appropriate discipline and consistency.

In recent years, cyber incidents targeting OT environments have demonstrated just how damaging a lack of asset visibility can be. Attackers often exploit forgotten devices, outdated firmware, or weakly segmented networks to establish initial access, then move laterally across interconnected systems, compromising critical assets and disrupting core operations.

An accurate and regularly maintained asset inventory closes those gaps by ensuring each component is known, categorized, assigned criticality, and protected according to its risk profile. While each operator should strive to collect every asset in their environment, CISA recommends that operators start by prioritizing assets based on criticality and evolve the list continuously until a complete record is captured.

An OT asset inventory is also foundational for alignment with industry standards. Whether it’s NIST, IEC 62443, or sector-specific frameworks, most cybersecurity best practices begin with the principle: “Know what you have.”

From Inventory to Action

The real value of an OT asset inventory comes when it is integrated into daily operations. With an asset inventory, operators can:

• Prioritize vulnerabilities based on criticality and exposure.

• Detect unauthorized devices before they become attack vectors.

• Support network segmentation efforts by mapping communication flows.

• Enable incident response teams to act quickly and accurately.

Having a complete and accurate OT asset inventory is the essential first step toward building defensible architecture and more resilient operations. This guidance serves as a strategic enabler for cyber defense actions and operational collaboration with CISA and other key stakeholders.

With a precise understanding of the assets within an operator’s infrastructure, Common Vulnerabilities and Exposures (CVEs) added to CISA’s Known Exploited Vulnerabilities Catalog or to stakeholder notifications and threat advisories become significantly more actionable and timelier—helping operators reduce risk proactively, before incidents escalate.

To support this effort, CISA offers tools and resources, including MALCOLM for network traffic analysis, no-cost Cyber Hygiene vulnerability scanning, the Cyber Security Evaluation Tool (CSET), and cross-agency support to help validate and manage asset data. Additionally, CISA provides support through regional Protective Security Advisors (PSAs), Cyber Security Advisors (CSAs), Emergency Communications Coordinators (ECCs), and Chemical Security Inspectors (CSIs).

Find out more about Industrial Cybersecurity Challenges and Solutions.